Analysis of transfer power of capacitive power transfer system

There are three method for wireless power transfer from the viewpoint of transfer field. The first is inductive power transfer (IPT) using magnetic field which is currently the most popular way to realize wireless power transfer. The second is wireless power transfer using radio wave. The third is capacitive power transfer (CPT) using electric field. There are only few studies about CPT because of small power density compared to another method due to small coupling capacitance. CPT is however investigated recently to utilize the advantages in CPT, such as simple structure of couplings, lightweight, low cost, position flexibility and high frequency applicability. In order to overcome this problem, a lot of CPT system were proposed using LC resonance. The authors have proposed a CPT system using one pulse switching active capacitor (OPSAC). The proposed system improves power transfer efficiency without LC resonance so that it is robust against parameter change. In this paper, the basic principle and characteristics of the proposed circuit is described at first. Next, transfer power of CPT system is analyzed with comparison between CPT with LC resonance and CPT with OPSAC.